Persuasive argument for using a boat broker - 5 opening emails

I work for a Yacht brokerage that sends many emails to prospective clients. We have seen many different approaches to closing a lead, but would like to know which approach works best. Boats range from $25-300,000+ You will provide a set of 5 opening emails to private sellers. Must research the industry standards(%10 commission), know boating lingo and demonstrate positive qualities. Multiple writers wanted.